Method of spinning filaments and spinneret for use therewith



Patented Mar. 4, 1952 IWETHOD OF SPINNING FILAMENTS AND SPINNERET FOR USE THEREWITH Rudolph S. B ley, Milligan College, Tenn., as-

signor to North American Rayon Corporation, New York, N. Y., a corporation of Delaware N Drawing. Application February 23, 1950, Serial No. 145,909

In the wet spinning of synthetic products a spinning solution is extruded through the minute orifices of a spinneret into a neutral, acid or alkaline spin bath to form filaments, films and the like therein. Since the spinneret is usually completely immersed in the spin bath it becomes contaminated by various impurities introduced into or formed in the spin bath by chemical reaction between the ingredients of the spinning solution and the spin bath. Generally such spinneret contaminations or incrustations comprise rings (for example, zinc sulphide rings) gradually accumulating on the inside of spinneret orifices and craters building up on the outside thereof. Since such spinneret incrustations gradually clog and close the fine orifices or slits of metallic spinnerets during the spinning process, the contaminated spinnerets must be replaced at frequent intervals to assure continuous spinning. This involuntary spinneret change is time-consuming and expensive.

Many attempts have been made heretofore to reduce or substantially inhibit spinneret in- .crustations by providing precious metal spinnerets with very thin coatings of waxy or oily substances (see U. S. Patents Nos. 2,100,581; 2,475,129; 2,483,783; 2,492,451), or by adding cation-active compounds to the spinning solution or spin bath (see U. S. Patents Nos. 2,125,031; 2,242,225). However, it has been found in actual practice that such waxy or oily coatings do not adhere to the spinnerets for sufiiciently long periods of time to become of real practical value in the spinning of synthetic products.

It is the primary object of this invention to provide metal spinnerets initially with a very thin coating of a substantially water-soluble cation-active complex compound of the Werner type, and then to convert this initial, soluble coating into a strongly adherent, hydrophobic coating comprising a polymerized complex compound of the Werner type.

Another object of the present invention is a metallic spinneret provided with a thin coating of a hydrophobic, polymerized complex chromium compound of the Werner type.

Other objects of this invention will become apparent to those skilled in the art from a study of this specification.

In accordance with Alfred Werners coordination theory many metals possess not only primary valences but also secondary or'auxiliary valences, and it is postulated that the particular metal atom draws to itself, in the form of a surrounding shell, and by forces other than by the primary valences, coordinated atoms or groups, usually six in number. The central metallic 8 Claims. (01. 18-8) atom together with its coordinated atoms or groups constitutes a nucleus, generally depicted as an octahedron, in which the metal is located in the center and the six coordinated atoms or groups located at the six points of the octahedron. The nucleus acts as the cation, and the atoms or groups outside the nucleus act as the anion of the compound. The anion is held to the cation by the primary valences. Metals such as chromium, cobalt, etc., are capable of forming complex compounds of the Werner type, while alkali metals are incapable of I doing so.

In accordance with this invention, saturated or unsaturated carboxylic acido groups having preferably at least 10 carbon atoms to induce surface-activity are coordinated with chromium,

to form water-soluble, cation-active complex compounds of the Werner type suitable for initially coating spinnerets. The carboxylic groups may be cyclic or acylic. The preparation of operative complex chromium compounds is clearly disclosed in U. S. Patent No. 2,273,040 to Iler of February 17, 1942, and U. S. Patent No. 2,356,161 to Iler of August 22, 1944. The anhydrous-chromium complex compounds have apparently the structure:

(Halogen) z.

in which R representsan alkyl, alkylene, aralkyl or aryl radical having at least 9 carbon atoms. stearato chromic chloride, palmitato vchrom'i'c chloride, laurato chromic chloride, oleato chromic chloride, stearato chromic fluoride, abietato chromic chloride, naphthenato chromic fluoride, methacrylato chromic chloride are examples, although not limited thereto, of complex compounds which may be used in accordance with this invention. When these anhydrous complex compounds are dissolved in water they form cation-active compounds. Upon dissolving for example stearato chromic chloride in a small amount of water a cation-active compound is obtained having probably the structure:

0 "Has 'inches (U. S. Patent No. 2,492,451).

When this cation-active compound is heated to a temperature of about 100 to 150 C. it polymerizes through the formation of Cr-O-Cr linkages and becomes hydrophobic, i. e., substantially water-insoluble.

The following example illustrates the prepara- 'tion of non-contaminating precious metal spinnerets for use in wet-spinning.

Example A carefully cleansed gold-platinum alloy spinneret is immersed for a few minutes in a ten percent aqueous solution of stearato chromic chloride. Excess solution is drained irom the spinneret which is then slowly heated in an oven to a temperature of about 140 C. The originally hydrophilic (water-soluble) coating polymerizes and becomes hydrophobic. The thin, adherent, hydrophobic coating thus formed will prevent spinneret incrustations for sumciently long periods of time when the treated spinneret is used in the wet spinning or viscose, casein, collagen and other spinning solutions which tend to incrustate spinneret OlifioGS. The stearato chromic chloride may be replaced by any other polymerizable complex compound of the Werner type provided the polymerization product becomes sufiiciently hydrophobic. The first hydrophilic coating of the cation-active complex compound may beformed on the spinneret by electrolysis or electrophoresis using the method set forth in U. 5. Patent No. 2,294,154 to Barthelemy et a1. It is also within the scope of this invention to provide the polymerized complex compound coating with at least one additional coating of a waxy or oily material and/or a surface-active compound (lauryl amine, polymerized ethylene oxide, etc.) which will tenaciously adhere to the hydrophobic polymerized complex compound of the Werner type. Compounds of the Werner type having an unsaturated acido group, for example methacrylato chromic chloride, will form coatings on spinnerets which may be further polymerized with unsaturated resin forming materials, such as allyl, vinyl and methacrylate monomers, under the influence of heat and peroxide catalysts to modify the final hydrophobic characteristics of polymerized coatings of the Werner type complex compounds. Although polymerization of the initial water-soluble coating is preferably achieved by the application of heat, nevertheless this result can be accomplished also by the chemical means disclosed in the aforesaid Iler patents.

Although this novel treatment can be applied to any metal, glass or plastic spinneret, it is of special value in connection with the coating of precious metal spinnerets used in the spinning of viscose and having an orifice area density factor K greater than 800 determined by the formula K=AD/S where D is the orifice density of the spinneret expressed as orifices per square inch, S is the periphery of the spinneret face in inches and A is the area of the spinneret face in square The concentration of the aqueous complex compound for the initial treatment of the spinneret is not criti-- cal and may be varied within wide limits.

Modifications of this invention will be recognized by those skilled in the art, and it is desired to cover all modificationsand variations coming within the scope of the appended claims.

I claim:

1. A spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type.

2. A spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex chromium compound of the Werner type.

3. A spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type in which a trivalent nuclear chromium atom is coordinated with an acyclic carboxylic acido group having at least 10 carbon atoms.

4. A spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type in which a trivalent nuclear chromium atom is coordinated with a carbocyclic acido group having at least 10 carbon atoms.

5. In a wet spinning process comprising extruding a spinning solution through the orifices of a spinneret into a spin bath to form filaments, films and the like therein, the improvement which comprises using a spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type.

6. In a wet spinning process comprising extruding a spinning solution through the orifices of a spinneret into a spin bath to form filaments, films and the like therein, the improvement which comprises using a spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex chromium compound of the Werner type.

7. In a wet spinning process comprising extruding a spinning solution through the orifices of a spinneret into a spin bath to form filaments, films and the like therein, the improvement which comprises using a spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type in which a trivalent nuclear chromium atom is coordinated with an acylic carboxylic acido group having at least 10 carbon atoms.

8. In a wet spinning process comprising extruding a spinning solution through the orifices of a spinneret into a spin bath to form filaments, films and the like therein, the improvement which comprises using a spinneret provided with an adherent coating of a hydrophobic substance, said substance comprising a polymerized complex compound of the Werner type in which a trivalent nuclear chromium atom is coordinated with a carbocyclic acido group having at least 10 carbon atoms.

RUDOLPH S. BLEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,273,040 Iler Feb. 17, 1942 2,356,161 Iler Aug. 22, 1944 2,483,783 Polak Oct. 4, 1949 2,515,697 Cresswell July 18,- 1950 

1. A SPINNERET PROVIDED WITH AN ADHERENT COATING OF A HYDROPHOBIC SUBSTANCE, SAID SUBSTANCE COMPRISING A POLYMERIZED COMPLEX COMPOUND OF THE WERNER TYPE. 